Bandwidth breakthrough A new fibre optic technology could increase internet bandwidth capacity by sending data along light beams that twist like a tornado rather than move in a straight line, say scientists.

The discovery comes as internet data traffic is reaching its limit amid mounting demand for bandwidth by users of smartphones and internet-enabled devices, creating problems for network providers.

The new technology uses optical vortices, which are like doughnut-shaped laser light beams. Also known as orbital angular momentum (OAM) beams, they were thought to be unstable in fibre until now.

An engineering professor at Boston University, Siddharth Ramachandran, found a way to make an optical fibre that can handle them.

Traditionally, bandwidth has been enhanced by increasing the number of colours, or wavelengths of data-carrying laser signals -- essentially streams of 1s and 0s -- sent down an optical fibre, where signals are processed according to colour.

Increasing the number of colours -- or channels -- has worked well since the 1990s when the method was introduced, but now that number is reaching physical limits.

An emerging strategy to boost bandwidth is to send the light through a fibre along distinctive paths, or modes from one end of the fibre to the other. Unlike the colour channels, data streams of 1s and 0s mix together so determining which stream data comes from requires computationally intensive and energy-hungry algorithms.

Ramachandran and Willner's approach combines both techniques packing several colours into each mode and uses several modes. But unlike conventional fibres, the data streams remain separate at the receiving end.

Using this technique, they showed it was possible to send a huge amount of data through a one-kilometre fibre, as much as 1.6 terabits per second, or the equivalent of transmitting eight Blu-Ray DVDs every second.